1. Field of the Invention
This invention relates to a fluid compressor for compressing a fluid, for example, refrigerant gas in a refrigerating cycle.
2. Description of the Related Art
Conventionally known are various compressors, including reciprocating compressors, rotary compressors, etc. In these conventional compressors, the compression section and drive parts, such as a crank shaft for transmitting a rotational force to the compression section, are complicated in construction, i.e., with many components being used in their construction. For higher compression efficiency, moreover, these conventional compressors should be provided with a check valve on the discharge side thereof. However, the pressure difference between two opposite sides of the check valve is so large that gas is likely to leak from the valve. Thus, the compression efficiency cannot be high enough. For solving these problems, the individual parts must be manufactured and assembled at high accuracies, resulting in a high manufacturing cost.
U.S. Pat. No. 2,401,189 and U.S. Pat. No. 2,527,536 disclose screw pumps each provided with a columnar rotary body having a suction end and a discharge end. The rotary body is arranged in a sleeve and has a spiral groove on its outer periphery. A spiral blade is slidably fitted in the groove. As the rotary body is rotated, a fluid, confined between two adjacent turns of the blade in the space between the outer peripheral surface of the rotary body and the inner peripheral face of the sleeve, is transported from one end of the sleeve to the other.
With the pumps described above, thrust exerted on the rotary body during operation increases friction between the rotary body and bearings, thereby deteriorating the efficiency of the pumps. In the pump disclosed in U.S. Pat. No. 2,527,536, two rotors are arranged opposed to each other so as to balance the thrust exerted on the rotary body. However, this pump still consists of many parts and has a complicated structure.
Accordingly, the conventional compressors have a problem that they must be provided with many parts and have a complicated structure so as to prevent the generation of thrust exerting on the rotary body.